The possibility of efficiently decomposing water into hydrogen and oxygen has attracted a great deal of research as a way of storing energy in the form of a clean burning fuel. The discovery that n-type titanium dioxide and strontium titanate will catalyze the photoelectrolysis of water means that water can be decomposed by sunlight with the addition of little or no other energy. Strontium titanate is an especially good catalyst for this purpose because its quantum efficiency in the absence of a bias voltage is about an order of magnitude higher than that obtained with titanium dioxide.
A major drawback in the use of strontium titanate for this purpose, however, is its high cost of preparation. Until now, n-type strontium titanate photo-electrodes were prepared by cutting slices from a single crystal, then reducing the slices in a hydrogen atmosphere at about 900.degree. C. Growing single crystal strontium titanate and preparing the n-type disk from the single crystals made the material too expensive for use in any commercial process.